1. Field of the Invention
Aspects of the present invention relate to an image processing apparatus and method, and more particularly, to an image processing apparatus and method which can prevent or reduce the deterioration of visibility of an image displayed on an image display device occurring under various lighting conditions when the brightness of ambient light is brighter than that of the image display device.
2. Description of the Related Art
Recently, a variety of digital devices that meet the diverse needs of consumers have come into wide use. These digital devices range from those having large-sized displays, such as computers and digital televisions (TVs), to those having small-sized displays, such as mobile phones, personal digital assistants (PDAs), and portable multimedia players (PMPs).
Unlike large-sized digital devices, small-sized digital devices, such as mobile phones, can be used not only in fixed settings but also in various locations, such as in dark rooms or in outdoor environments under direct sunlight. Therefore, required is a method of providing appropriate brightness and contrast of an image displayed under a given external luminance to optimally display an image. In other words, when the external luminance is high, the brightness and contrast of the displayed image must be increased.
However, it is difficult to clearly determine a specific method of adjusting the brightness and the contrast of the displayed image according to changes in external luminance. The same is true for saturation. That is, it is also difficult to determine a specific method of adjusting saturation according to changes in the brightness and the contrast of the displayed image.
In this regard, various related technologies to prevent or reduce the deterioration of visibility in digital devices have been suggested, including display technologies based on external luminance information.
These related technologies may be classified into technologies for improving an image quality through signal processing and technologies for improving an image quality through a device change. In particular, the technologies for improving the image quality through signal processing include a color tonal contrast processing technology and a luminance tonal contrast processing technology. The related technologies for improving image quality through signal processing are disclosed, for example, in U.S. Pat. No. 6,727,489 and Korean Patent Publication No. 2005-13767.
Specifically, U.S. Pat. No. 6,727,489 relates to an adaptive color processing technology using information regarding the brightness and color of ambient light of a projector or a reflective surface. However, the adaptive color processing technology fails to consider saturation and requires information regarding both the brightness and color of an external light source. In addition, Korean Patent Publication No. 2005-13767 relates to a technology for improving the contrast of a displayed image by minimizing de-fading according to changes in the luminance of the ambient light. However, this technology is simply directed to improving the contrast based on the luminance and does not consider the luminance and the saturation of an image.